Laboratory dose-induced thermoluminescence (TL) sensitivity changes have been observed in natural quartz at doses in excess of 250 Gy. This observation has a direct Implication for environmental dosimetry and luminescence geochronology. We suggest a new variant of thermoluminescence dating based on dose-dependent sensitivity changes. When established fully, this approach can potentially extend the quartz-based TL chronology up to a million years. Electron spin resonance studies on the same samples and using the same irradiation schedule indicate growth of a new centre at g = 2.0033. A conceptual framework to explain these observations has been attempted. (C) 1998 . .